It must bug Neil Simon that his detested ex-sister-in-law is getting regular royalty checks for “The Odd Couple.”

Arlene Simone (she Frenchified the name with an “e”) is still mad at Neil because he didn’t give his brother, Danny Simon, any credit for helping write his most successful comedy, which was turned into a hit movie and TV series and continues to be performed all over the world.

“Danny wrote a 14-page treatment. It was his story. Danny was Felix, a neat freak, hypochondriac living with another guy who’d gotten divorced, an agent named Roy Gerber,” Arlene, on a visit from Los Angeles, told me at Flex Mussels restaurant on East 82nd Street.

“Danny was truly devastated when he was given no credit. It was wrong. It was unfair.”

Neil assuaged his guilt by giving Danny 16 percent of the play’s royalties, which Arlene now splits with her son, a federal judge in Oregon.

“Neil knows I don’t like him,” Arlene said. “It must hurt him I’m getting these checks.”